diff options
Diffstat (limited to 'drivers/firmware/arm_scmi/mailbox.c')
-rw-r--r-- | drivers/firmware/arm_scmi/mailbox.c | 329 |
1 files changed, 329 insertions, 0 deletions
diff --git a/drivers/firmware/arm_scmi/mailbox.c b/drivers/firmware/arm_scmi/mailbox.c new file mode 100644 index 0000000000..b8d470417e --- /dev/null +++ b/drivers/firmware/arm_scmi/mailbox.c @@ -0,0 +1,329 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * System Control and Management Interface (SCMI) Message Mailbox Transport + * driver. + * + * Copyright (C) 2019 ARM Ltd. + */ + +#include <linux/err.h> +#include <linux/device.h> +#include <linux/mailbox_client.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/slab.h> + +#include "common.h" + +/** + * struct scmi_mailbox - Structure representing a SCMI mailbox transport + * + * @cl: Mailbox Client + * @chan: Transmit/Receive mailbox uni/bi-directional channel + * @chan_receiver: Optional Receiver mailbox unidirectional channel + * @cinfo: SCMI channel info + * @shmem: Transmit/Receive shared memory area + */ +struct scmi_mailbox { + struct mbox_client cl; + struct mbox_chan *chan; + struct mbox_chan *chan_receiver; + struct scmi_chan_info *cinfo; + struct scmi_shared_mem __iomem *shmem; +}; + +#define client_to_scmi_mailbox(c) container_of(c, struct scmi_mailbox, cl) + +static void tx_prepare(struct mbox_client *cl, void *m) +{ + struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl); + + shmem_tx_prepare(smbox->shmem, m, smbox->cinfo); +} + +static void rx_callback(struct mbox_client *cl, void *m) +{ + struct scmi_mailbox *smbox = client_to_scmi_mailbox(cl); + + /* + * An A2P IRQ is NOT valid when received while the platform still has + * the ownership of the channel, because the platform at first releases + * the SMT channel and then sends the completion interrupt. + * + * This addresses a possible race condition in which a spurious IRQ from + * a previous timed-out reply which arrived late could be wrongly + * associated with the next pending transaction. + */ + if (cl->knows_txdone && !shmem_channel_free(smbox->shmem)) { + dev_warn(smbox->cinfo->dev, "Ignoring spurious A2P IRQ !\n"); + return; + } + + scmi_rx_callback(smbox->cinfo, shmem_read_header(smbox->shmem), NULL); +} + +static bool mailbox_chan_available(struct device_node *of_node, int idx) +{ + int num_mb; + + /* + * Just check if bidirrectional channels are involved, and check the + * index accordingly; proper full validation will be made later + * in mailbox_chan_setup(). + */ + num_mb = of_count_phandle_with_args(of_node, "mboxes", "#mbox-cells"); + if (num_mb == 3 && idx == 1) + idx = 2; + + return !of_parse_phandle_with_args(of_node, "mboxes", + "#mbox-cells", idx, NULL); +} + +/** + * mailbox_chan_validate - Validate transport configuration and map channels + * + * @cdev: Reference to the underlying transport device carrying the + * of_node descriptor to analyze. + * @a2p_rx_chan: A reference to an optional unidirectional channel to use + * for replies on the a2p channel. Set as zero if not present. + * @p2a_chan: A reference to the optional p2a channel. + * Set as zero if not present. + * + * At first, validate the transport configuration as described in terms of + * 'mboxes' and 'shmem', then determin which mailbox channel indexes are + * appropriate to be use in the current configuration. + * + * Return: 0 on Success or error + */ +static int mailbox_chan_validate(struct device *cdev, + int *a2p_rx_chan, int *p2a_chan) +{ + int num_mb, num_sh, ret = 0; + struct device_node *np = cdev->of_node; + + num_mb = of_count_phandle_with_args(np, "mboxes", "#mbox-cells"); + num_sh = of_count_phandle_with_args(np, "shmem", NULL); + dev_dbg(cdev, "Found %d mboxes and %d shmems !\n", num_mb, num_sh); + + /* Bail out if mboxes and shmem descriptors are inconsistent */ + if (num_mb <= 0 || num_sh <= 0 || num_sh > 2 || num_mb > 3 || + (num_mb == 1 && num_sh != 1) || (num_mb == 3 && num_sh != 2)) { + dev_warn(cdev, + "Invalid channel descriptor for '%s' - mbs:%d shm:%d\n", + of_node_full_name(np), num_mb, num_sh); + return -EINVAL; + } + + /* Bail out if provided shmem descriptors do not refer distinct areas */ + if (num_sh > 1) { + struct device_node *np_tx, *np_rx; + + np_tx = of_parse_phandle(np, "shmem", 0); + np_rx = of_parse_phandle(np, "shmem", 1); + if (!np_tx || !np_rx || np_tx == np_rx) { + dev_warn(cdev, "Invalid shmem descriptor for '%s'\n", + of_node_full_name(np)); + ret = -EINVAL; + } + + of_node_put(np_tx); + of_node_put(np_rx); + } + + /* Calculate channels IDs to use depending on mboxes/shmem layout */ + if (!ret) { + switch (num_mb) { + case 1: + *a2p_rx_chan = 0; + *p2a_chan = 0; + break; + case 2: + if (num_sh == 2) { + *a2p_rx_chan = 0; + *p2a_chan = 1; + } else { + *a2p_rx_chan = 1; + *p2a_chan = 0; + } + break; + case 3: + *a2p_rx_chan = 1; + *p2a_chan = 2; + break; + } + } + + return ret; +} + +static int mailbox_chan_setup(struct scmi_chan_info *cinfo, struct device *dev, + bool tx) +{ + const char *desc = tx ? "Tx" : "Rx"; + struct device *cdev = cinfo->dev; + struct scmi_mailbox *smbox; + struct device_node *shmem; + int ret, a2p_rx_chan, p2a_chan, idx = tx ? 0 : 1; + struct mbox_client *cl; + resource_size_t size; + struct resource res; + + ret = mailbox_chan_validate(cdev, &a2p_rx_chan, &p2a_chan); + if (ret) + return ret; + + if (!tx && !p2a_chan) + return -ENODEV; + + smbox = devm_kzalloc(dev, sizeof(*smbox), GFP_KERNEL); + if (!smbox) + return -ENOMEM; + + shmem = of_parse_phandle(cdev->of_node, "shmem", idx); + if (!of_device_is_compatible(shmem, "arm,scmi-shmem")) { + of_node_put(shmem); + return -ENXIO; + } + + ret = of_address_to_resource(shmem, 0, &res); + of_node_put(shmem); + if (ret) { + dev_err(cdev, "failed to get SCMI %s shared memory\n", desc); + return ret; + } + + size = resource_size(&res); + smbox->shmem = devm_ioremap(dev, res.start, size); + if (!smbox->shmem) { + dev_err(dev, "failed to ioremap SCMI %s shared memory\n", desc); + return -EADDRNOTAVAIL; + } + + cl = &smbox->cl; + cl->dev = cdev; + cl->tx_prepare = tx ? tx_prepare : NULL; + cl->rx_callback = rx_callback; + cl->tx_block = false; + cl->knows_txdone = tx; + + smbox->chan = mbox_request_channel(cl, tx ? 0 : p2a_chan); + if (IS_ERR(smbox->chan)) { + ret = PTR_ERR(smbox->chan); + if (ret != -EPROBE_DEFER) + dev_err(cdev, + "failed to request SCMI %s mailbox\n", desc); + return ret; + } + + /* Additional unidirectional channel for TX if needed */ + if (tx && a2p_rx_chan) { + smbox->chan_receiver = mbox_request_channel(cl, a2p_rx_chan); + if (IS_ERR(smbox->chan_receiver)) { + ret = PTR_ERR(smbox->chan_receiver); + if (ret != -EPROBE_DEFER) + dev_err(cdev, "failed to request SCMI Tx Receiver mailbox\n"); + return ret; + } + } + + cinfo->transport_info = smbox; + smbox->cinfo = cinfo; + + return 0; +} + +static int mailbox_chan_free(int id, void *p, void *data) +{ + struct scmi_chan_info *cinfo = p; + struct scmi_mailbox *smbox = cinfo->transport_info; + + if (smbox && !IS_ERR(smbox->chan)) { + mbox_free_channel(smbox->chan); + mbox_free_channel(smbox->chan_receiver); + cinfo->transport_info = NULL; + smbox->chan = NULL; + smbox->chan_receiver = NULL; + smbox->cinfo = NULL; + } + + return 0; +} + +static int mailbox_send_message(struct scmi_chan_info *cinfo, + struct scmi_xfer *xfer) +{ + struct scmi_mailbox *smbox = cinfo->transport_info; + int ret; + + ret = mbox_send_message(smbox->chan, xfer); + + /* mbox_send_message returns non-negative value on success, so reset */ + if (ret > 0) + ret = 0; + + return ret; +} + +static void mailbox_mark_txdone(struct scmi_chan_info *cinfo, int ret, + struct scmi_xfer *__unused) +{ + struct scmi_mailbox *smbox = cinfo->transport_info; + + /* + * NOTE: we might prefer not to need the mailbox ticker to manage the + * transfer queueing since the protocol layer queues things by itself. + * Unfortunately, we have to kick the mailbox framework after we have + * received our message. + */ + mbox_client_txdone(smbox->chan, ret); +} + +static void mailbox_fetch_response(struct scmi_chan_info *cinfo, + struct scmi_xfer *xfer) +{ + struct scmi_mailbox *smbox = cinfo->transport_info; + + shmem_fetch_response(smbox->shmem, xfer); +} + +static void mailbox_fetch_notification(struct scmi_chan_info *cinfo, + size_t max_len, struct scmi_xfer *xfer) +{ + struct scmi_mailbox *smbox = cinfo->transport_info; + + shmem_fetch_notification(smbox->shmem, max_len, xfer); +} + +static void mailbox_clear_channel(struct scmi_chan_info *cinfo) +{ + struct scmi_mailbox *smbox = cinfo->transport_info; + + shmem_clear_channel(smbox->shmem); +} + +static bool +mailbox_poll_done(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer) +{ + struct scmi_mailbox *smbox = cinfo->transport_info; + + return shmem_poll_done(smbox->shmem, xfer); +} + +static const struct scmi_transport_ops scmi_mailbox_ops = { + .chan_available = mailbox_chan_available, + .chan_setup = mailbox_chan_setup, + .chan_free = mailbox_chan_free, + .send_message = mailbox_send_message, + .mark_txdone = mailbox_mark_txdone, + .fetch_response = mailbox_fetch_response, + .fetch_notification = mailbox_fetch_notification, + .clear_channel = mailbox_clear_channel, + .poll_done = mailbox_poll_done, +}; + +const struct scmi_desc scmi_mailbox_desc = { + .ops = &scmi_mailbox_ops, + .max_rx_timeout_ms = 30, /* We may increase this if required */ + .max_msg = 20, /* Limited by MBOX_TX_QUEUE_LEN */ + .max_msg_size = 128, +}; |